While one of important human motor functions is a function of center of gravity shifting, such function of center of gravity shifting may be deteriorated in a patient having a problem with body movement due to a disease or injury, or an elderly person, etc. Since a person who has an inadequate function of center of gravity shifting cannot make a smooth center of gravity shift such that the body weight is applied alternately to the left and right legs, for example, basic motion such as walking may be hindered. Therefore, center of gravity shifting training for enabling smooth center of gravity shifting is widely introduced in, for example, the field of rehabilitation.
On the other hand, there has been proposed a system which includes a measurement device (load detection means) disposed at the feet of a user (subject) and adapted for detecting the center of the total load applied to each leg of the user, wherein the system causes a display device to display an image showing the center of gravity position of the user evaluated from the output of the measurement device (see, for example, document 1, “JP 7-275307 A”). In the system described in document 1, a target icon (target image) which works as the target for center of gravity shifting is displayed on the display device, and the user is allowed to perform center of gravity shifting training to shift the center of gravity position in coordination with the movement of the target icon such that the image indicating the center of gravity position is overlapped on the target icon. Further, in the system described in document 1, a plurality of shifting patterns of the target icon are prestored in accordance with the training objective of the user so that the shifting pattern can be selected in accordance with the user.
In the system described in document 1, however, since a human selects a shifting pattern of the target icon from the plurality of shifting patterns prepared in advance, it is difficult to individually select a shifting pattern respectively suitable for each user when, for example, an unspecified large number of users are targeted. That is, the level of deterioration in the function of center of gravity shifting varies from person to person even among people having similar symptoms (for example, people whose function of the right leg is deteriorated), and it is not desirable to make all the users having similar symptoms perform rigidly uniform center of gravity shifting training from the viewpoint of the efficiency of training.